Investigation of the microstructure and property for supersulphated cement concrete and the portland cement concrete

The mechanical property, hydration heat and microstructure of supersulphated cement(SSC), Portland slag cement(PSC) and ordinary Portland cement(OPC) were comparatively investigated. The hydration products and micro-structure of three different concretes were measured by XRD, SEM, TG-DSC, FTIR. Compressive strength was used to evaluate the mechanical property. The results show that, in the same mix proportion of concrete, the strength of SSC is lower than those of PSC and OPC at 3 curing days, however, the strength of SSC increases rapidly with surpassing that of PSC after the ages of 7 days and reach 40.5 MPa which keep up with that of OPC at 28 day ages. The hydration products of SSC arc ettringite and calcium silicate hydrate(C-S-H), ettringite and residual gypsum arc encapsulated closely by C-S-H gel, forming a dense and homogenous structure, there is no calcium hydroxide being the remarkable difference between the SSC and Portland cement, the content of calcium hydroxide in three cements follow the order of OPC>PSC>SSC. The hydration heat of three cements arc in the order of OPC>PSC>SSC, and SSC is found to be one kind of cement which has rather low heat of hydration.